IF there is a boy just across the court from your flat, or in the next house, to whom you want to send messages or any light merchandise, here is a railway that runs on a string or cord that will furnish all the fun you would want, and at the same time be a practical way to send things back and forth, provided you fix the "air line" across the court or some space where it will not interfere with traffic.

The railway will cost you only your time, as all the things needed to make it are common about the house.

The main part is a cigar box for the body part, then some bits of stout wire, some pine sticks, a piece of curtain pole for the pulleys, some stout cord, and some scraps of board.

From the frame, which is formed of two side sticks F and a central space block, as shown at b, wire supports W hang down. These pass through holes in the frame, as shown at the top, and then, dropping on either side of it, end in hooks which stick into holes in the sides of the cigar box.

Thus the box is supported from the frame, and the weight of the whole structure is brought low, so that the pulleys cannot upset . on the cord line or track.

The cord, which runs under the pulleys, passes around a pulley D supported to turn at each end of the line. The drawing shows this pulley mounted on a wall outside, where it can easily be reached. This pulley has a crank on the side.

Passing over the top of the pulley at either end, the cord line runs back underneath and finally ties to the box through holes bored for the purpose. In tying here the line is drawn tight.

The end pulleys should be made large if you want to get any speed out of the car, but if you expect to carry weights of any size use a smaller one.

When both pulleys are arranged to turn easily and are made readily accessible to the operators at either end of the line, we are ready to see how the scheme will work.

You can easily see that when you turn the crank at one end of the line the cord will pass over and back, or vice versa.

Thus, as the cord travels, the car will be pulled along, the pulleys rolling over the cord, which will also move under them in an opposite direction.

The speed of the car will depend on the speed with which you turn the crank and the size of the end pulley.

I will leave the dimensions entirely to the maker, as all cigar boxes are not the same size, .but you can easily figure out the size required by the material you have at hand.

The pulleys are made from sections sawed off a curtain pole. First bore a hole through the center, - a quarter-inch hole. Then saw off a section half an inch wide, marking it carefully beforehand, so that you will be sure and get it straight.

Put these sections in a vise and, with a three-cornered file, file a groove all the way around the rim, making it fairly deep and as even in depth as possible. The deeper it is, within the side limits, the less your wheels will be likely to run off the track.

This done, fit wooden axles into the central holes, making them a tight fit and about an inch long. Into the ends of these drive pins or small brads, shown at n for the spindles, taking care that they are exactly in the center and that the wheels run true when they are all in place.

For the sidepiece of the frame F cut sticks about as long as the cigar box and separate them by a wooden block b, a little wider than the length of the wooden axles in the wheels. Then punch holes in the sidepieces and fit the brads n of the pulleys through holes bored so that they come exactly opposite and both pairs parallel. This mounts the wheels, and forms the upper part or "truck" of our car.

The supporting wires are bent, as shown in the small sketch, and fitted through holes in the truck frame sides F as shown. These wires are a little heavier than baled hay wire. The wires fasten to the box too simply to need explanation.

The driving pulleys are cut from half-inch wood, the circles being cut roughly with a saw and then laid out flat on a board and trimmed down true to the line you have drawn with a compass, a sharp knife being used. A small hole is bored in the center of this, through which a screw spindle will fit, fastening into the bracket piece K, seen next to the pulley at the left. This piece is nailed to the baseboard D you see attached to the wall.

The pulley is grooved in the same way as the small one, with a three-cornered file. The crank handle is a spool with the flanges trimmed off, fastened to the pulley side by a screw through its center.

The drawing shows clearly how the line is strung, and the length over which you can operate it depends only on the strength of the cord you have at hand.